Linkages for toy building blocks, such as those made by LEGO®, Duplo®, Mega Bloks, Built to Rule, K'nex, Kre-O, and others, provide limited degrees of movement and positioning in the three dimensional plane for the blocks they connect.
Flexible plastic cables, string, plastic rods, and plastic tubes have been used to connect building blocks, as illustrated and described in U.S. Pat. Nos. 5,433,549, 5,733,168, 6,000,984, 6,213,839, 6,461,215, 6,676,474, 6,843,700, and PCT/DK1991/000373. Other prior art systems are Lego® Technic Sets 5118, 7471, 8002, 8074, 8412, 8437, 8440, 8444, 8445, 8457, 8479, 8482, 8483, 8485, 8828, 8836, 8839, 8856, and 9748.
As shown in FIG. 1A, an end P1 is connected to a bendable plastic rod P2 via neck P3. Front end P1, rod P2, and neck P3 are shaped to be received in a complementary slot P11-P13 of the receiver block P10. Thus, a plastic rod P2 with necks P3 and ends P1 disposed on either terminus of the rod P2 is used to tether blocks to which receiver block P10 may couple, provided the necks P3 and ends P1 are capable of receipt in the receiver block slots P11-P13. In an alternative arrangement shown by FIG. 1B, a receiver block P10 is comprised of a jaw P5, a mouth P6, and a tooth P7 that engages a recess/neck P3 in a plastic rod P2 received within block P10. In this arrangement, the prior art receiver block P10 relies on plastic-on-plastic coupling between tooth P7 and recess P3 to maintain rod P2 in the block P10, e.g., a crimping connection.
All of these linkage systems suffer disadvantages in terms of the reduction in strength from repeated use and/or exposure to heat, weakness when loaded in a direction perpendicular to their cross-section, and/or lack of ability to be bent in any number of conformations while also substantially maintaining a conformation in three-dimensional space, e.g., wilting or buckling in response to loads.